INTRODUCTION:

Karnataka in Peninsular India due to unique topographical features supports over 2,187 perennial and 29,588 seasonal tanks with an estimated water spread area of 2,96,316 hectares (David et. al. 1974). Many of these could be easily categorised as wetlands going by the general definition of the Ramsar Convention. Over 2,300 major tanks in the state, cover about 15% of its geographic area and 2,600 have an atchkat (area under irrigation) of more than 40 ha, covering all biogeographic regions and offer habitat for a variety of aquatic and semi-aquatic flora and fauna.

The ecology of all wetlands is subjected to wide and frequent fluctuations due to tropical climatic conditions (heavy precipitation and rapid evaporation). In Karnataka this is true for most areas except the Western Ghats and northern maidan (plains) region. Further, the peripheral areas possess very high biological production as well as rich biodiversity. The biodiversity ranges from microorganisms to fish, amphibians, reptiles and birds (apart from waterfowl). Thus, wetlands support diverse fauna and flora and their crucial habitats. Hence, it is important to preserve them.

The number of tanks in Bangalore urban (Metropolitan region) has dwindled in the last 2-3 decades. Similar threats are being faced by most of the other urban wetland habitats in Karnataka. A survey of some major wetlands in the selected districts of Karnataka was conducted apart from a questionnaire-based survey (modified from Asian Waterfowl Census, South Asia).

RESULTS:

Wetlands irrigating less than 2,000 ha account for about 33% of the total irrigated area in the state and hence form an important component of the state's economy (Rama Prasad and K.R. Sreenivasan, 1990). Large wetland areas have been taken over for non-wetland purposes. A total of 642 tanks in 15 districts were surveyed and the following observations were made.

1) The waterfowl census has served as biological indicators for gauging the health and productivity of wetlands in the absence of wider ecological information. However, the effort still appears seriously inadequate when all the wetlands of the state are considered. There is an urgent need to create awareness on the need for protection, conservation and restoration of wetlands for posterity.

2) Three wetlands, viz. Badrana (Badana) kere in Kolar district, and Bellandur Tank and Byramangala Reservoir (in Bangalore) were of global importance as they supported more than 20,000 birds. However, Bellandur tank due to inflow of urban sewage is highly polluted. It is unfortunate that none of the three wetlands have legal protection.

3) The rapid loss of wetland habitat and biodiversity is mainly due to the growing population and resultant urbanization and its many negative impacts like encroachment in catchment area, sedimentation, pollution, etc. (Sridhar, S., 1992).

4) There is inadequate data on water quality, limnology, hydrology, sustainable uses, watershed development and conservation of wetland values. Information on groundwater and landscape development though important is ignored.

5) Wetlands around cities and towns are being used for easy and inexpensive disposal of urban sewage.

6) Visits to selected wetlands revealed that pristine waterfowl habitats like the heronries in Ranganthittu Bird Sanctuary in Mysore, Gudavi and Mandaggade in Shimoga are often prone to floods. The habitat quality of these wetlands is also changing so that they are no longer able to support the waterfowl through out the year.

7) Lakes and ponds near cities and towns are becoming eutrophic with excessive growth of vegetation (especially water hyacinth - Eichhornia) and algal blooms (green and brown). Most of these waterbodies are loosing seasonality and their ecological values are not being sustained. The introduction of exotic fish species has greatly upset the endemic fish diversity.

8) About three decade back, 262 tanks existed within the Metropolitan limits of Bangalore city, which has dwindled to 117 (Table - 1).

TABLE 1: NUMBER OF TANKS IN AND AROUND BANGALORE CITY

Year	Number in Corporation area	Number in BDA area	Number in the proposed BMRDA area
1931	26	115	-
1971	17	95	60
1981*	5	16	11

About 30 tanks are present but 14 of them have shrunk in size. Number of tanks and ponds in BDA (Bangalore Development Authority) are 114 and 106, respectively. There were about 389 tanks at the beginning of the 19th Century.

9) Water from wetlands is increasingly drawn for agricultural purposes, as in Mandya, Hassan, Tumkur and Chikmagalur. Wetland birds are frequently seen in cultivated tracts surrounding the wetlands. The agricultural run-off, with high pesticide content, affects the wetlands and the birds dependent on them.

10) In hilly regions, water from coffee pulpers is being drained into natural streams, rivulets and ponds. As a result, the wetlands are seriously affected and ecologically destroyed.

11) From 1985 onwards, on-shore development of river basins like Tungabhadra, Cauvery, Hemavathy and other rivers has been so rampant that fish resources have depleted seriously affecting the biodiversity considerably. Mega projects like Cogentrix, Enron, etc., have threatened major wetlands in coastal and hill regions of Karnataka especially the Western Ghats. Nuclear power projects like Kaiga have further dampened prospects of reviving vulnerable and fragile ecosystems like mangroves, estuaries, rivers and ocean basins and the associated shore regions.

12) Coastal wetlands represent complex ecosystems, overgrown by Pandanus shrub or hedges. At some places along the length of the canal or stream, the plant detritus gets continuously accumulated and its decomposition results in organic matter accumulation at bottom of the channels / streams. The biological productivity and biodiversity of native species appears to be low in such patches. Better shore management practices are urgently required around these wetlands.

13) There are many specialised habitats and some, uniquely support only some species specifically. In Dharwad, for instance, a survey of 54 tanks in 1993 revealed that the pacific golden plover Pluvialis fulva, glossy ibis Plegadis falcinellus, wooly-necked stork Ciconia episcopus and white stork Ciconia cinonia are rare and present only at selected wetlands (Uttangi, J.C., 1993).

14) The Pollution Control Board and the Department of Forests, Environment and Ecology should set stringent standards for water quality. The decline in water quality has threatened the biodiversity in and around wetlands. The problem exists even within wildlife sanctuaries such as Muthodi, Kemmanagundi, etc.

15) Wetlands in the urban and suburban areas face imminent threat. Leaving good shore space (up to 2 km) can protect wetlands in rural areas. This buffer area can be vegetated, which will enhance the productivity of the wetlands too. The edges of tanks/wetlands need to be fenced well and if possible, vegetation can be maintained all around. Effluents from industries, urban sewage, solid waste especially plastics, should not be diverted to or dumped into wetlands.

16) Management plans for each of the 25 National Parks/Sanctuaries in Karnataka supporting a vast stretch of diversified wetlands need immediate attention.

RECOMMENDATIONS: Waterfowl census and habitat monitoring

Regular waterfowl counts along with status of habitat information need to be carried out from time to time. Large wetlands other than reservoirs should be documented for their waterfowl conservation value. Awareness programmes, campaigns concerning local wetlands, bird observations as a hobby etc should be launched and sustained. The highly successful model of transfer of urban wetlands in Bangalore for care and protection by the forest department should be immediately applied to all cities and towns of the state.

Loss and fragmentation of catchment areas

Open lands near tanks/lakes should be protected and preserved. Area up to the high water level (HWL) and associated areas beyond the HWL have to be identified, marked off and suitably managed. All efforts should be made to ensure conservation of rainwater runoff through suitable ecological measures, preventing pollution en route. Common lands like gomal lands (grass lands for grazing), groves and others in catchment zone should be protected and improved ecologically.

Sewage and other effluents

Proper management and treatment of effluents is urgently required. Provisions of the Environment Protection Act and Water Act should be effectively used and enforced for better conservation of lakes. Sanitary and watershed management guidelines should be enforced for all lakes and other drinking water sources in the state. Efforts should be made to see that only rainwater runoff enters such waterbodies / wetlands etc. Vegetation associated with sewage inflow (water hyacinth), should be continuously removed till effluent inflows are controlled. Special efforts should be made for coastal areas and Western Ghats (coffee pulping wastes). Excessive use of fertilizers and pesticides, especially in rural areas, needs to be assessed, monitored and the effects studied for developing suitable strategies to improve the quality of inflowing water.

Silting and sedimentation

Activities in shore and catchment areas that increase silting and sedimentation (erosion due to poor catchment status) have to be controlled or modified. Assessments of silting and sedimentation as well as measures taken should be made frequently

Mudlifting and brickmaking

Silt from catchment areas through erosion, natural ecological processes and human activities; accumulate at the bottom of waterbodies. The silt has been used as a resource for brick and tile making. In recent times, this mudlifting activity has become highly unscientific and ecologically damaging, causing indirect effects on the biodiversity, productivity and other socio-economic aspects. Brick making and mudlifting should be restricted to silt from deeper areas of the lake. Shores should not be disturbed. Restrictions of distances, about 250 m - 500 m for urban habitats and up to 1 km for rural areas, from the high water level should be introduced.

Encroachment of tank bed and shore areas

Encroachments of all nature should be strictly prevented. Illegal encroachments should be removed and the wetlands are to be restored. Watershed development and conservation of wetland variety and values need to be addressed in a scientific and holistic manner. Cultivation in drying margins, which contributes to sedimentation, need to be prevented. Proper landscape improvement activities for catchment and shore areas need to be adopted.

Poaching of wildlife

Ecological threats to wetlands also affect the security and conservation of associated birdlife and minor wildlife. Major habitats supporting large populations of birds whether resident/migratory need to be immediately protected. Important congregation sites of birds need to be protected. Wildlife and Environment Protection Acts have to be enforced to prevent/control poaching and the Wildlife Wing of the Forest Department should setup an electronic database (accessible to all) listing all major wetlands and bird habitats for effective protection/monitoring by concerned citizens.

Assessment of water quality

Water quality and retention time is a key to the sustenance of any wetland habitat. Water colour is one of the indicators of ecological disturbances. Periodic assessments of both water quality and quantity need to be carried out. Direct entry of sewage and industrial effluent needs to be prevented and ensuring proper treatment of wastes is very important.

Resource use, biodiversity management and recreation

Protection measures need to be carried out in a holistic manner like any other wildlife habitats. Evaluation of already launched restoration efforts should be carried out for drawing up future strategies since, no two wetlands can be similar ecologically and otherwise. Awareness campaigns need to be carried out frequently highlighting their importance.

Coastal wetlands

These are important as waterfowl habitats. Threat to mangroves and swampy wetlands (like Aghanashini and Kali estuaries) need to be urgently looked into and direct inflow of wastes need to be prevented. Water quality and biological parameters need to monitored and assessed from time to time, especially biological productivity and biodiversity. It may be worthwhile to identify and declare some wetland expanses in the region as protected areas in terms of wetland wildlife habitats. These may have mangroves and thus additionally help in erosion control efforts.

REFERENCES:

BIBLIOGRAPHY:

Address:

1.) Institute for Natural Resources Conservation,
Education,
Research and Training (INCERT),
No 10,
Sirur Park,
B Street,
Seshadripuram,
Bangalore -20,
Phone: 3364142/3364682,
Email: navbarat@blr.vsnl.net.in

2.) Foundation for Nature Exploration and Environmental Conservation (NEC),
Bangalore